EP0130376A2 - Low-voltage dual-phase logic circuit - Google Patents
Low-voltage dual-phase logic circuit Download PDFInfo
- Publication number
- EP0130376A2 EP0130376A2 EP84106170A EP84106170A EP0130376A2 EP 0130376 A2 EP0130376 A2 EP 0130376A2 EP 84106170 A EP84106170 A EP 84106170A EP 84106170 A EP84106170 A EP 84106170A EP 0130376 A2 EP0130376 A2 EP 0130376A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- transistor
- coupled
- emitter
- collector
- logic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/02—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits using specified components
- H03K19/08—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits using specified components using semiconductor devices
- H03K19/082—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits using specified components using semiconductor devices using bipolar transistors
- H03K19/086—Emitter coupled logic
Definitions
- the invention relates to a low-voltage dual-phase logic circuit, and in particular to a logic circuit of the current switch emitter-follower type.
- Figures 1 and 2 of the drawings show examples of prior art logic circuits, respectively taken from the IBM Technical Disclosure Bulletin and US-A-3,509,640, Fig. 1 showing a half-current switch circuit and Fig. 2 a low-voltage inverter circuit.
- the conductive channels (collector-to-emitter paths) of transistors 12 and 13 are coupled in parallel, with the collectors thereof being connected through a resistor 11 to a positive power supply potential V H and the emitters through a resistor 14 to a negative power supply potential V L.
- the collectors of the transistors 12 and 13 are also applied to the base of an emitter-follower output transistor 15, the collector of which is connected directly to V H and the emitter of which is passed through a resistor 16 to V L.
- the logic NOR of input signals A and B which are applied to the bases of the transistors 12 and 13, respectively, is produced at the emitter output terminal 17 of the transistor 15.
- the base of the transistor 15 is pulled negatively, thereby lowering the current in the transistor 15, and hence causing the output terminal 17 to be pulled negatively through the resistor 16.
- both of the input signals A and B are in their negative or DOWN state, the transistors 12 and 13 are turned off, thereby permitting base current to flow into the base of the transistor 15 through the resistor 11. This turns on the transistor 15 strongly, pulling the output terminal 17 positively.
- an input signal is applied to the base of a transistor 21, of which the collector is connected through a resistor 24 to the positive power supply potential V H and the emitter through a resistor 26 to the negative power supply potential V D .
- a Schottky-barrier diode 25 is connected in parallel with the resistor 24.
- the collector of the transistor 21 feeds the base of a transistor 22, which is connected in an emitter-follower configuration.
- the collector of the transistor 22 is connected directly to the positive power supply potential V H , and its emitter to the collector a third transistor 23, the base of which also receives the input signal.
- a resistor 27 connects the emitter of the transistor 23 to V L .
- a resistor 28 is connected between the junction point between the transistors 22 and 23 and V L .
- the transistors 21 and 23 are off and the transistor 22 on. Therefore, the output signal ⁇ on the output terminal 29 is taken positively by the transistor 22.
- the transistors 21 and 23 are on and the transistor 22 is in a low current state. Thus, the output signal T on the terminal 29 is in the DOWN state. An inversion of the input signal is thereby produced.
- the prior art circuits of Fig. 1 are in fact capable of operating from a low power supply voltage, for instance, with a difference of 2 volts between V H and V L , and do have a quite excellent power-performance advantage, nevertheless, the noise margins for these circuits are not as high as is desired for many applications. Also, the prior art circuits of Figs. 1 and 2 do not provide an in-phase output, that is, the outputs from both are inverted signals. Further, it is desirable in many situations to provide a logic circuit in which the delay times through the circuit is less than what can be attained with the circuits of Figs. 1 and 2.
- a current switch logic circuit including current switch means for producing a signal representing a predetermined logic function, such as a logical OR, NOR or inversion, of at least one input logic signal in response to that logic signal and a reference potential applied to the current switch means, the reference potential being employed for distinguishing UP and DOWN levels of the at least one input logic signal, and means for varying the reference potential in phase opposition to the at least one, input logic signal.
- a predetermined logic function such as a logical OR, NOR or inversion
- phase opposition is meant 1 that, when the input signal is moving in the positive direction, the reference potential is moving in the negative direction, and vice versa.
- the means for varying the reference potential may be an inverter which receives the same at least one input logic signal as the current switch means.
- the current switch means may be composed of a transistor having a control electrode coupled to receive the at least one input logic signal, a first current channel electrode coupled to receive the reference potential, and a second current channel electrode on which is produced the signal representing the desired predetermined logic function of the input logic signal or signals.
- control electrode is meant the base electrode in the case of a bipolar transistor and the gate in the case of a field-effect transistor, and what is meant by “first current channel electrode” and “second current channel electrode” are the emitter and collector electrodes in the case of a bipolar transistor and the source and drain electrodes in the case of a field-effect transistor.
- An output stage may be provided for producing an output logic signal, having the desired UP and DOWN logic signal levels, in accordance with the signal representing the predetermined logic function of the input logic signal produced by the current switch means.
- the output stage may provide true and complementary (uninverted and inverted, respectively) output signals.
- the invention can be practiced by a dual-phase current switch logic circuit in which in-phase and inverted outputs of an input phase-splitting transistor circuit are coupled to respective emitter-follower transistor circuits, with the in-phase output coupled to its corresponding emitter-follower transistor circuit via a reference transistor.
- a transistor inverter feedback circuit is coupled between the input to the input-phase splitting transistor circuit and a reference node of the reference transistor so as to vary the reference potential at the reference node in phase opposition to the phase of the input signal.
- a logic circuit having a high noise margin and one which is capable of operating from low circuit voltages is thereby obtained.
- a low-voltage dual-phase logic circuit indicated generally by reference numeral 40, constructed in accordance with the teachings of the invention will now be described.
- An input signal on an input terminal 51 is applied to bases of transistors T l and T2.
- the collectors of the transistors Tl and T2 are coupled to the positive power supply potential V H through resistors 41 and 42, respectively, while their emitters are coupled to the negative power supply potential V L through respective resistors 44 and 45.
- the resistance values of the resistors 42, 45 and 46 are chosen so that the voltage swings on the collector of the transistor T2 will be less than those on the collector of the transistor Tl.
- the collector output 53 of the input transistor Tl is connected to the base of an emitter-follower output transistor T4, the collector of which is connected directly to V H and the emitter of which is connected through a resistor 48 to V L .
- the collector output of the transistor T2 is applied to the base of a transistor T3, the collector of which drives the base of a second output emitter-follower transistor T5 and is coupled to the positive power supply potential V H through a resistor 43.
- the emitter of the transistor T3 is connected directly to the emitter of the input transistor Tl forming a current switch, that is, to the reference potential node 52 thereof.
- the collector of the output transistor T5 is connected directly to V H , and its emitter through a resistor 47 to V b .
- An uninverted output signal ⁇ on a terminal 49 is produced at the emitter of the transistor T5 and an inverted output T on a terminal 50 at the emitter of the transistor T4.
- Fig. 4 shows a modification of the circuit of Fig. 3 in the form of an OR/NOR gate circuit.
- transistors T6 and T7 have been added, to the bases of which a second input signal B is applied.
- An input signal A is applied to the bases of transistors Tl and T2.
- the transistors T6 and T7 are connected in parallel with the transistors Tl and T2, respectively.
- the circuit construction is the same as that of Fig. 3.
Landscapes
- Engineering & Computer Science (AREA)
- Logic Circuits (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Computing Systems (AREA)
- General Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
Abstract
Description
- The invention relates to a low-voltage dual-phase logic circuit, and in particular to a logic circuit of the current switch emitter-follower type.
- Low-voltage (approximately 2 volts) single-phase current switch emitter-follower type logic circuits are known in the art. Examples for relevant publications are the following:
- - L. Weiss and T.S. Jen, "Achieving Subnanosecond Delays Using Feedback with the Current-Switch", IEEE J. Solid State Circuits, Vol. SC-1, pp. 86-94, December 1966;
- - H.M. Rein and R. Ranfft, "Improved Feedback ECL Gate with Low Delay-Power Product for the Subnanosecond Region", IEEE J. Solid State Circuits, Vol. SC-12, pp. 80-82, February 1977;
- - J.B. Hughes, "Comments on 'Improved Feedback ECL Gate with Low Delay-Power Product for the Subnanosecond Region"', IEEE J. Solid State Circuits, Vol. SC-13, pp. 276-278, April 1978;
- - IBM Technical Disclosure Bulletin, Vol. 23, No. 7A, December 1980, "Half-Current Switch Circuit" by A. Bass et al., pp. 2813-2814;
- - US-A-3,509,363;
- - US-A-4,283,640.
- Figures 1 and 2 of the drawings show examples of prior art logic circuits, respectively taken from the IBM Technical Disclosure Bulletin and US-A-3,509,640, Fig. 1 showing a half-current switch circuit and Fig. 2 a low-voltage inverter circuit. In the half-current switch circuit of Fig. 1, the conductive channels (collector-to-emitter paths) of
transistors resistor 14 to a negative power supply potential V L. The collectors of thetransistors follower output transistor 15, the collector of which is connected directly to VH and the emitter of which is passed through aresistor 16 to V L. - Operationally, the logic NOR of input signals A and B, which are applied to the bases of the
transistors emitter output terminal 17 of thetransistor 15. Specifically, when either of thetransistors transistor 15 is pulled negatively, thereby lowering the current in thetransistor 15, and hence causing theoutput terminal 17 to be pulled negatively through theresistor 16. On the other hand, when both of the input signals A and B are in their negative or DOWN state, thetransistors transistor 15 through the resistor 11. This turns on thetransistor 15 strongly, pulling theoutput terminal 17 positively. - In the low-voltage inverter circuit of Fig. 1, an input signal is applied to the base of a
transistor 21, of which the collector is connected through aresistor 24 to the positive power supply potential VH and the emitter through aresistor 26 to the negative power supply potential VD. A Schottky-barrier diode 25 is connected in parallel with theresistor 24. The collector of thetransistor 21 feeds the base of atransistor 22, which is connected in an emitter-follower configuration. The collector of thetransistor 22 is connected directly to the positive power supply potential VH, and its emitter to the collector athird transistor 23, the base of which also receives the input signal. Aresistor 27 connects the emitter of thetransistor 23 to VL. A resistor 28 is connected between the junction point between thetransistors - When the input signal is in its DOWN state, the
transistors transistor 22 on. Therefore, the output signalφ on theoutput terminal 29 is taken positively by thetransistor 22. On the other hand, when the input signal is in the UP state, thetransistors transistor 22 is in a low current state. Thus, the output signal T on theterminal 29 is in the DOWN state. An inversion of the input signal is thereby produced. - Although the prior art circuits of Fig. 1 are in fact capable of operating from a low power supply voltage, for instance, with a difference of 2 volts between VH and VL, and do have a quite excellent power-performance advantage, nevertheless, the noise margins for these circuits are not as high as is desired for many applications. Also, the prior art circuits of Figs. 1 and 2 do not provide an in-phase output, that is, the outputs from both are inverted signals. Further, it is desirable in many situations to provide a logic circuit in which the delay times through the circuit is less than what can be attained with the circuits of Figs. 1 and 2.
- Jen et al. in United States Patent No. 3,509,363 describe a current switch type transistor logic circuit in which a delayed and in-phase replica of an input logic signal is employed as a reference to a current source supplying current to the input stage of the circuit. This has the advantage of providing a reference signal which is close to the value of the input signal just before a change in state of the input signal occurs. Although some speed advantage may thereby be obtained, nevertheless, because the reference signal must be delayed with respect to the input signal, optimum delay times through the circuit cannot be obtained.
- Accordingly, it is an object of the present invention to provide a current switch logic circuit having simultaneously a high-noise margin and fast switching speed while being able to operate from low power supply voltages.
- Yet further, it is an object of the invention to provide such a current switch logic circuit which has both inverted and non-inverted outputs.
- These, as well as other objects of the invention, are met by a current switch logic circuit including current switch means for producing a signal representing a predetermined logic function, such as a logical OR, NOR or inversion, of at least one input logic signal in response to that logic signal and a reference potential applied to the current switch means, the reference potential being employed for distinguishing UP and DOWN levels of the at least one input logic signal, and means for varying the reference potential in phase opposition to the at least one, input logic signal.
- By "phase opposition" is meant 1 that, when the input signal is moving in the positive direction, the reference potential is moving in the negative direction, and vice versa. The means for varying the reference potential may be an inverter which receives the same at least one input logic signal as the current switch means. The current switch means may be composed of a transistor having a control electrode coupled to receive the at least one input logic signal, a first current channel electrode coupled to receive the reference potential, and a second current channel electrode on which is produced the signal representing the desired predetermined logic function of the input logic signal or signals.
- By "control electrode" is meant the base electrode in the case of a bipolar transistor and the gate in the case of a field-effect transistor, and what is meant by "first current channel electrode" and "second current channel electrode" are the emitter and collector electrodes in the case of a bipolar transistor and the source and drain electrodes in the case of a field-effect transistor. An output stage may be provided for producing an output logic signal, having the desired UP and DOWN logic signal levels, in accordance with the signal representing the predetermined logic function of the input logic signal produced by the current switch means. The output stage may provide true and complementary (uninverted and inverted, respectively) output signals.
- Further, the invention can be practiced by a dual-phase current switch logic circuit in which in-phase and inverted outputs of an input phase-splitting transistor circuit are coupled to respective emitter-follower transistor circuits, with the in-phase output coupled to its corresponding emitter-follower transistor circuit via a reference transistor. A transistor inverter feedback circuit is coupled between the input to the input-phase splitting transistor circuit and a reference node of the reference transistor so as to vary the reference potential at the reference node in phase opposition to the phase of the input signal. A logic circuit having a high noise margin and one which is capable of operating from low circuit voltages is thereby obtained.
- Details of two examples of embodiments of the invention are hereafter described with reference to the appended drawings in which:
- Fig. 1 is a schematic diagram of a prior art half-current switch circuit;
- Fig. 2 is a schematic diagram of a prior art low-voltage inverter circuit;
- Fig. 3 is a schematic diagram of a first embodiment of a logic circuit of the invention;
- Fig. 4 is a schematic diagram of a second embodiment of a logic circuit of the invention; and
- Fig. 5 is a waveform diagram used to explain the operation of the circuit of Fig. 3.
- Referring now to Fig. 3, a low-voltage dual-phase logic circuit, indicated generally by
reference numeral 40, constructed in accordance with the teachings of the invention will now be described. An input signal on aninput terminal 51 is applied to bases of transistors Tl and T2. The collectors of the transistors Tl and T2 are coupled to the positive power supply potential VH throughresistors respective resistors resistors collector output 53 of the input transistor Tl is connected to the base of an emitter-follower output transistor T4, the collector of which is connected directly to VH and the emitter of which is connected through aresistor 48 to VL. The collector output of the transistor T2 is applied to the base of a transistor T3, the collector of which drives the base of a second output emitter-follower transistor T5 and is coupled to the positive power supply potential VH through aresistor 43. The emitter of the transistor T3 is connected directly to the emitter of the input transistor Tl forming a current switch, that is, to the referencepotential node 52 thereof. The collector of the output transistor T5 is connected directly to VH, and its emitter through aresistor 47 to Vb. An uninverted output signal φ on aterminal 49 is produced at the emitter of the transistor T5 and an inverted output T on aterminal 50 at the emitter of the transistor T4. - The operation of the circuit of Fig. 3, which is an inverter/buffer circuit, will be explained with reference to the waveform diagrams of Fig. 5. When the input signal on the
terminal 51 is in the DOWN state, both of the transistors Tl and T2 are turned off. Base current can then flow to the transistor T4, thereby taking theoutput terminal 50 to the UP logic level. The transistor T2 is turned off, thereby supplying base current to the transistor T3 through the biasing produced by theresistors output terminal 49 in the DOWN logic state. The above-described state is illustrated in the left-hand portion of Fig. 5, that is, the portion of Fig. 5 before the input signal starts to rise. - When the input signal on the
input terminal 51 starts to rise, the collectors of the transistors Tl and T2 will move in the negative direction. Hence, the base drive to the transistor T3 is reduced, thereby reducing the amount of current supplied through the transistor T3 to thenode 52 at the junction of the emitter of the transistors Tl and theresistor 44. This has the effect of driving thenode 52 in phase opposition to the input signal, and causing Tl to conduct sooner. The result is to widen the noise margin of the circuit and to increase the signal switching speed at lower power supply voltages than previously possible. - When the input signal on the terminal 51 reaches the UP level, the current in the transistor T4 will be decreased and that in the transistor T5 increased. Thus, inverted and non-inverted versions of the input signal on
input terminal 51 are provided onoutput terminals - Fig. 4 shows a modification of the circuit of Fig. 3 in the form of an OR/NOR gate circuit. In the circuit of Fig. 4, transistors T6 and T7 have been added, to the bases of which a second input signal B is applied. An input signal A is applied to the bases of transistors Tl and T2. The transistors T6 and T7 are connected in parallel with the transistors Tl and T2, respectively. Otherwise, the circuit construction is the same as that of Fig. 3. By following through the circuit operation in the manner described above, it can easily be appreciated by one of ordinary skill in the art that, in this case, the output signals on
terminals
Claims (9)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US50967583A | 1983-06-30 | 1983-06-30 | |
US509675 | 1983-06-30 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0130376A2 true EP0130376A2 (en) | 1985-01-09 |
EP0130376A3 EP0130376A3 (en) | 1987-01-07 |
Family
ID=24027636
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84106170A Withdrawn EP0130376A3 (en) | 1983-06-30 | 1984-05-30 | Low-voltage dual-phase logic circuit |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0130376A3 (en) |
JP (1) | JPS6010918A (en) |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3509363A (en) * | 1965-10-14 | 1970-04-28 | Ibm | Logic switch with active feedback network |
US3628053A (en) * | 1969-12-22 | 1971-12-14 | Ibm | Logic switch with variable threshold circuit |
EP0028292A1 (en) * | 1979-10-05 | 1981-05-13 | International Business Machines Corporation | All-NPN transistor driver and logic circuit |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57210726A (en) * | 1981-06-22 | 1982-12-24 | Hitachi Ltd | Driver circuit |
-
1984
- 1984-05-16 JP JP9670284A patent/JPS6010918A/en active Pending
- 1984-05-30 EP EP84106170A patent/EP0130376A3/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3509363A (en) * | 1965-10-14 | 1970-04-28 | Ibm | Logic switch with active feedback network |
US3628053A (en) * | 1969-12-22 | 1971-12-14 | Ibm | Logic switch with variable threshold circuit |
EP0028292A1 (en) * | 1979-10-05 | 1981-05-13 | International Business Machines Corporation | All-NPN transistor driver and logic circuit |
Non-Patent Citations (4)
Title |
---|
IBM TECHNICAL DISCLOSURE BULLETIN, vol. 21, no. 6, November 1978, pages 2363,2364, New York, US; A. BRUNIN: "Reference free current switch circuit * |
IBM TECHNICAL DISCLOSURE BULLETIN, vol. 23, no. 7A, December 1980, pages 2813,2814, New York, US; A. BASS et al.: "Half-current switch circuit" * |
IEEE ELECTRO, vol. 7, May 1982, pages 1-8, Section 10/2, New York, US; B. GILLINGS: "New design techniques yield very high speed bipolar 8-and 12-bit microprocessor compatible analog-to-digital converters" * |
IEEE JOURNAL OF SOLID-STATE CIRCUITS, vol. SC-1, no. 2, December 1966, pages 86-94, New York, US; L. WEISS et al.: "Achieving subnanosecond delays using feedback with the current switch" * |
Also Published As
Publication number | Publication date |
---|---|
EP0130376A3 (en) | 1987-01-07 |
JPS6010918A (en) | 1985-01-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5909127A (en) | Circuits with dynamically biased active loads | |
KR900008051B1 (en) | Logic circuitry | |
US5148061A (en) | ECL to CMOS translation and latch logic circuit | |
JP2975122B2 (en) | Level conversion circuit | |
US5045730A (en) | Electrical circuitry providing compatibility between different logic levels | |
KR910001882B1 (en) | Buffer circuit | |
US4897564A (en) | BICMOS driver circuit for high density CMOS logic circuits | |
US4980579A (en) | ECL gate having dummy load for substantially reducing skew | |
US3900746A (en) | Voltage level conversion circuit | |
EP0173288A2 (en) | Voltage level converting circuit | |
EP0219867B1 (en) | Logic circuit | |
EP0131205B1 (en) | Current source control potential generator for ecl logic circuits | |
JP2858270B2 (en) | ECL / CML pseudo rail circuit, cut-off driver circuit and latch circuit | |
US3946246A (en) | Fully compensated emitter coupled logic gate | |
US5059827A (en) | ECL circuit with low voltage/fast pull-down | |
US4536665A (en) | Circuit for converting two balanced ECL level signals into an inverted TTL level signal | |
US4458162A (en) | TTL Logic gate | |
US3183370A (en) | Transistor logic circuits operable through feedback circuitry in nonsaturating manner | |
JPS61127226A (en) | Emitter coupled logic circuit | |
US5338980A (en) | Circuit for providing a high-speed logic transition | |
US5331225A (en) | BiCMOS logic circuit with bipolar transistor and MOS transistor formed on the same semiconductor substrate | |
JPH02268515A (en) | Bi-cmos logic circuit | |
EP0130376A2 (en) | Low-voltage dual-phase logic circuit | |
US4868904A (en) | Complementary noise-immune logic | |
EP0564390A2 (en) | High-speed bipolar-field effect transistor (BI-FET) circuit |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): DE FR GB |
|
17P | Request for examination filed |
Effective date: 19841123 |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Kind code of ref document: A3 Designated state(s): DE FR GB |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN |
|
18W | Application withdrawn |
Withdrawal date: 19870206 |
|
R18W | Application withdrawn (corrected) |
Effective date: 19870206 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: BANKER, DENNIS CLARK Inventor name: BARISH, ARNOLD EUGENE Inventor name: EHRLICKMAN, EDWARD LEWIS |